NASA readies Juno spacecraft for mission to Jupiter (photos)

On a five-year journey to Jupiter, the largest planet in our solar system, Juno will attempt to sleuth out some details of Jupiter's structure and origin.

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Jupiter

If you take everything else in our solar system (not including the sun), it would all fit inside Jupiter.

In terms of understanding our solar system, NASA says, Jupiter's importance cannot be underestimated. Scientists believe it was the first planet to be formed in our solar system and that it might therefore hold clues to the history, development, and composition of all the other planets.

At 1,300 times the volume of Earth and more than twice the mass of all other planets combined, Jupiter's enormous size and powerful gravity have influenced the formation of all other celestial bodies in our solar system. And unlike Earth, Jupiter's composition has not changed since it was formed more than 5 billion years.

Now, NASA intends to learn a little more about our giant neighbor.

NASA today will launch the Juno spacecraft, sending it on a six-year mission to study Jupiter. After traveling more than 400 million miles to reach its destination, a trip that will take five years, the spacecraft will orbit Jupiter, skimming to within 3,100 miles above the planet's cloud tops every 11 days. Over the course of that year-long portion of the mission, Juno is expected to orbit the planet approximately 33 times.

This true-color shot of Jupiter was composed of four images taken by NASA's Cassini spacecraft. The resulting image was projected onto a globe to create the same effect you'd get from a camera capable of squeezing the entire planet into its field of view. The image resolution? About 89 miles per pixel, according to NASA.

The little black spot in the lower left is a shadow cast by Europa, one of Jupiter's four largest moons.

Prepping Juno

Juno will carry eight instruments to study Jupiter's internal structure and gravity field, measure water on the planet and ammonia within the atmosphere, as well as map its powerful magnetic field and observe its iconic auroras.

Plaque on Juno

A plaque dedicated to the famous astronomer Galileo Galilei is seen here, affixed to NASA's Juno spacecraft.

The plaque is printed in Galileo's own handwriting and was provided by the Italian Space Agency. It includes his image and a passage written by him in 1610 in some of his observations of Jupiter, now archived in the Biblioteca Nazionale Centrale in Florence.

"On the 11th it was in this formation--and the star closest to Jupiter was half the size than the other and very close to the other so that during the previous nights all of the three observed stars looked of the same dimension and among them equally afar; so that it is evident that around Jupiter there are three moving stars invisible till this time to everyone."

Solar cells

Thousands of solar cells are located on Juno's 11 panels, four on each of two of the spacecraft's 250-pound wings. The third wing has three panels and is outfitted with a boom at the end that carries the spacecraft's magnetometer, seen here on the left.

These instruments will map the planet's magnetic field with a high level of accuracy, observing its variations over time, and giving scientists a look inside the planet, helping to understand how and where Jupiter's powerful magnetic field is generated.

Each of the two vector magnetometers carries with it a pair of non-magnetic star cameras to determine its orientation in space, sort of like an interstellar GPS.

Juno's solar arrays

To provide enough power to heat the spacecraft and provide instrument power, Juno's solar arrays have to be big. Jupiter is five times farther from the sun than Earth, and the sunlight there is 25 times weaker.

The arrays are 29 feet long and 8 feet wide. Despite their size, they will generate between 400 and 450 watts of power from within Jupiter's orbit--only enough energy to run four standard light bulbs.

Atlas payload fairing

The twin sections of the Atlas payload fairing are moved closer to the Juno spacecraft during work to enclose the spacecraft for launch. The payload nose cone will be mounted aboard one of the world's most powerful rockets, the 650-ton Atlas V 551.

Astrotech payload processing facility

At the Astrotech payload processing facility near Kennedy Space Center in Florida, the taper-tipped Atlas V 551 rocket payload fairing that will enclose the Juno spacecraft is shown here on July 25 as it gets secured on a transporter, and readied to be moved out to the Space Launch Complex 41.

The fairing will protect the spacecraft from the impact of aerodynamic pressure and heating during ascent and will be jettisoned once the spacecraft is outside Earth's atmosphere.

Juno preparations

The five-year flight to Jupiter will put extreme stress on Juno, and balance and proper center of gravity are crucial. Aside from the sun, Jupiter is considered one of the harshest planetary environments.

In addition to extreme cold temperatures and intense, damaging radiation, Juno will reach extremely stressful speeds along its journey.

After performing what is known as a gravitational slingshot out of Earth's orbit in Jupiter's direction, Juno will coast along, picking up speed due to Jupiter's large size and huge gravitational pull.

Eventually, as it closes in on Jupiter, Juno will reach speeds of 150,000 miles per hour, making it the fastest human-made object ever, before igniting its thrusters and slowing down to make the transition into Jupiter's orbit.

Juno on the rotation stand

Preparing the craft on June 16, technicians at Astrotech's payload processing facility in Titusville, Fla., watch as NASA's Juno spacecraft is tested for center of gravity, weight, and balance on a rotation stand.

After being affixed to a mount at Astrotech's Hazardous Processing Facility in Titusville, Fla., technicians will load Juno with the hydrazine and nitrogen tetroxide propellant necessary for orbiting maneuvers and the attitude control system.

Because of the massive distances that will be between the control center on Earth and Juno when it arrives at Jupiter, the spacecraft cannot be controlled by joystick. Even using radio signals traveling at the speed of light, it will take 45 minutes to send a message, and another 45 minutes to get a response.

Technicians can steer Juno by firing main engines or thrusters, but the commands must be well planned and sent ahead of time.

Protective cover removed

With its protective cover removed, technicians prepare to fuel the Juno spacecraft on June 27 inside Astrotech's Hazardous Processing Facility in Titusville, Fla.

Hydrazine is typically used for most spacecraft because of its stored energy. Engineers won't need to do a lot of driving and steering of Juno on its five-year trip out to Jupiter. It will coast most of the way and get pulled along by Jupiter's gravitational forces. One critical maneuver, however, will take place in 2016, as the spacecraft gets inserted into Jupiter's orbit.

Solid rocket boosters

Developed by Lockheed Martin, the Atlas V uses a standard common core booster with an RD-180 dual chamber engine, up to five strap-on solid rocket boosters, a Centaur in either the Single-Engine Centaur or the Dual-Engine Centaur configuration, and one of several payload fairings.

This particular Atlas V rocket is designated "551"--meaning it carries a 5-meter payload fairing (5), which holds Juno, with 5 solid rocket boosters (5), and a single Centaur engine (1) for the second stage--therefore making up the Atlas V-551 Launch Vehicle.

Juno at dawn

At dawn on July 27 at Cape Canaveral Air Force Station's Space Launch Complex 41, the payload fairing, holding the Juno spacecraft, arrives at the launch pad to be mounted atop the Atlas rocket stacked in the Vertical Integration Facility.

United Launch Alliance Atlas V rocket

The first stage of a United Launch Alliance Atlas V rocket is lifted into the Vertical Integration Facility at Launch Complex 41 on June 13.

It will take Juno five years to reach Jupiter and begin its year of research work, but the launch team will know about an hour after launch if all their work paid off.

"In real time, we'll immediately start to see power generated, we'll see temperatures increasing on the panels, and we'll see the vehicle respond to the fact that wings deployed," said Russ Gehling, the solar array subsystem's lead engineer with Lockheed Martin. "We'll get all that data in. That's how we'll assess that the wings are out and the spacecraft is safe" and on its way to Jupiter, he said.